CartQuantity匹配查询不存在错误 [英] CartQuantity matching query does not exist ERROR

问题描述

我正在尝试获取查询集中的最新/最新号码:

Hi I'm trying to get the newest/latest number in a query set:

我为此使用此代码行:

CartQuantity.objects.filter(customer=customer).values_list('cquantity', flat=True).get(pk=-1)

这是查询集的外观:

<bound method QuerySet.last of <QuerySet [4, 4, 4, 2, 4, 4, 5, 6, 5, 14, 10, 12]>>  # need last number(12)

我尝试了上面的代码，但收到错误消息:

I tried the code above but I get an Error message:

store.models.CartQuantity.DoesNotExist:CartQuantity匹配查询不存在.

store.models.CartQuantity.DoesNotExist: CartQuantity matching query does not exist.

这是我的模型:

class CartQuantity(models.Model):
    customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, blank=True, null=True)
    cquantity = models.IntegerField(default=0, null=True, blank=True)

有人知道如何解决错误或以其他方式获取最新号码(在这种情况下为查询集中的号码12)吗?

Does anyone know how to fix the error or another way of getting the newest number(in this case number 12 in the query set)?

推荐答案

CartQuantity.objects.filter(customer = customer).values_list('cquantity'，flat = True)[-1]

或

CartQuantity.objects.filter(customer = customer).values_list('cquantity'，flat = True).last()

或

CartQuantity.objects.filter(customer = customer).values_list('cquantity'，flat = True).reverse()[0]

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